JPH03224256A - Cooling equipment for electronic machinery and apparatus - Google Patents

Abstract

PURPOSE:To increase heat transmission by using simple constitution and little energy, and remarkably improve cooling effect, by arranging piezoelectric vibrators so as to face an electronic apparatus as a body to be cooled, and applying high frequency vibration to refrigerant. CONSTITUTION:Piezoelectric vibrators 11 fixed on a stand 12 are arranged so as to face semiconductor elements 21 as bodies to be cooled. These are accommodated in a vessel 4, and refrigerant 3 like fluorocarbon whose electric insulating properties are excellent is made to circulate by external power (pump or the like). Lost heat quantity of the elements 21 is delivered to the flowing refrigerant 3, and further is cooled by an external heat exchanger. When a high frequency current is applied to the piezoelectric vibrators 11, they generate high frequency vibration, which reaches the elements 21 via the refrigerant 3. By the high frequency vibration, disturbance is generated in the state of the refrigerant on the heat conducting surfaces of the elements 21, so that the heat transmission can remarkably be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cooling device for cooling electronic equipment by immersing it in an electrically insulating refrigerant.

[Conventional technology]

Conventionally, methods such as natural air cooling and forced air cooling have been used to cool electronic devices. In recent years, semiconductor devices have become highly integrated and densely packaged, and electronic devices that have a large amount of heat loss per unit area are cooled by being directly immersed in a highly electrically insulating refrigerant, such as a fluorocarbon liquid. A so-called refrigerant immersion cooling system has been put into practical use. This refrigerant immersion cooling method can be roughly divided into (1) a method that cools by convection heat transfer;
2) There is a method of cooling by boiling heat transfer.

Cooling methods using convection heat transfer include natural convection cooling, in which electronic devices are immersed in a stationary refrigerant liquid tank, and forced convection cooling, in which electronic devices are immersed in a refrigerant flowing by external power. be.

On the other hand, methods for cooling by boiling heat transfer use a refrigerant with a boiling point lower than the heat generation temperature of the electronic device, and the pool boiling cooling method (for example, in practical use (Refer to Publication No. 129195/1982) and forced convection boiling cooling method (for example, Japanese Utility Model Application No. 61-1
(Refer to Publication No. 3949) In some cases, the pressure in the container in which these refrigerants are sealed is reduced from atmospheric pressure and boiled. In this case, the refrigerants boil at a low temperature, so it is A refrigerant with a boiling point higher than the exothermic temperature can also be used.

By the way, in heat transfer between a solid and a liquid, a thermal boundary layer (hereinafter referred to as the temperature boundary layer) is formed on the solid surface, and the large temperature gradient of this temperature boundary layer causes heat transfer from the solid surface to the surrounding liquid. is hindered. Therefore, in order to improve heat transfer from the solid surface to the surrounding liquid, it is necessary to thin or eliminate this thermal boundary layer so that the solid surface and the surrounding liquid are in direct contact. . Therefore, there is a method of forcibly flowing the refrigerant using external power to remove the temperature boundary layer and improve heat transfer. Specifically, there is a method in which a stirrer equipped with rotary blades is installed in a container to cause the refrigerant to flow, or a method in which the electronic device is immersed in the refrigerant that is pressurized with a pump or the like to form a jet state. In addition, in such an apparatus, there is a method of placing a turbulence promoting structure near the cooling surface to make the flow state turbulent and further improve heat transfer.

(Problem to be solved by the invention) In order to enhance the cooling effect in the refrigerant immersion cooling system,
As mentioned above, the refrigerant is forced to flow using external power, and a turbulence promoting structure is placed near the cooling surface to make this flow state turbulent and improve heat transfer. The temperature boundary layer, which is the main cause of heat transfer, is in close contact with the solid surface, and it is difficult to sufficiently remove it using the above-mentioned method, so there is a certain limit to the improvement of heat transfer.

An object of the present invention is to provide a cooling device that has a simple configuration and dramatically increases the cooling effect when cooling electronic equipment using a refrigerant immersion cooling method.

[Means to solve the problem]

In order to solve the above-mentioned problems, the electronic device cooling device of the present invention includes: an electronic device to be cooled; and one or more piezoelectric devices installed on a base and disposed opposite to the electronic device. The vibrator and the vibrator are immersed in an electrically insulating refrigerant, and these are housed in a container. The refrigerant is circulated by external power, and the refrigerant is cooled while applying the pressure to the circulating refrigerant by applying high-frequency vibrations. Allow your body's electronics to cool down. Further, an electronic device to be cooled and one or more piezoelectric vibrators installed on a base and placed facing the electronic device are immersed in an electrically insulating refrigerant, and these are sealed. The refrigerant is housed in a container with a space left above the liquid level of the refrigerant, and a heat exchanger is provided in this space, and the piezoelectric vibrator applies high frequency vibration to the refrigerant while cooling the electronic equipment to be cooled. Do it like this. Furthermore, the base on which the piezoelectric vibrator is installed forms part of the container. Furthermore, a resonator that resonates at the vibration frequency of the piezoelectric vibrator and has directivity is added to the piezoelectric vibrator.

[Effect]

According to the present invention, a piezoelectric vibrator applies high frequency vibration to the refrigerant,
This vibration propagates through the refrigerant and reaches the heat transfer surface of the electronic device. Two-dimensional waves are constantly present in this high-frequency vibration field, which causes disturbances in the state of the refrigerant on the heat transfer surface, effectively removing the temperature boundary layer and improving the heat transfer. In addition, when boiling occurs on the heat transfer surface, high-frequency vibrations are applied to the bubbles attached to the heat transfer surface, promoting bubble stratification from the heat transfer surface, making the heat transfer extremely difficult. improves. Furthermore, since the piezoelectric vibrator is installed on the base and attached near the heat transfer surface of the electronic device, the energy of high frequency vibrations efficiently reaches the heat transfer surface. Furthermore, since a resonator that resonates at the vibration frequency and has directivity is added to the piezoelectric vibrator, the energy of high-frequency vibration reaches the heat transfer surface more efficiently, and heat transfer is significantly improved.

〔Example〕

FIG. 1 is a sectional view of a cooling device according to an embodiment of the present invention.

In this example, a semiconductor device is used as the electronic device to be cooled! The case is shown below. 2 is a semiconductor device to be cooled, and a substrate 2
A semiconductor element 21 is attached to 2. The piezoelectric vibrator 11 is installed on a base 12, and the semiconductor element 21 of the object to be cooled
placed opposite.

These are housed in a container 4, within which a refrigerant 3 is circulated by an external power source, such as a pump. The second refrigerant is cooled by an external heat exchanger (not shown). As the refrigerant 3, a refrigerant with high electrical insulation properties, such as fluorocarbon, is used. The amount of heat lost in the semiconductor element 21 is transferred to the flowing refrigerant 3. Of course, a certain amount of cooling is still performed as it is, but when a high-frequency current is applied to the piezoelectric vibrator 11, the piezoelectric vibrator 11 generates high-frequency vibrations, which are applied to the coolant 2 and propagate through the coolant to the semiconductor element. reach This high-frequency vibration causes disturbances in the state of the coolant on the heat transfer surface of the semiconductor element, improving heat transfer.

In the structure shown in FIG. 1, one piezoelectric vibrator 11 is installed in correspondence with each semiconductor element 21, but one piezoelectric vibrator 11 may be made to correspond to a plurality of semiconductor elements 21. , or vice versa. FIG. 2 shows a different embodiment,
A base on which a piezoelectric vibrator is installed forms a part of the container 4. This reduces the size of the cooling device. The operating principle of cooling is the same as that shown in FIG.

FIG. 3 shows a further different embodiment; whereas the embodiments of FIGS. 1 and 2 required external power for refrigerant circulation, in this embodiment no external power is required for refrigerant circulation. Not necessary. In Figure 3, like Figures 1 and 2, the object to be cooled is a semiconductor! It is a sectional view of a cooling device in the case of J purchase. 2
1 is a semiconductor device to be cooled, and a semiconductor element 21 is attached to a substrate 22. The pressure T4 vibrator 11 is installed on a base 12 and is disposed facing the semiconductor element 21 of the object to be cooled.

These are immersed in a refrigerant liquid 31 and housed in a sealed container 4 leaving a space 41 above the refrigerant level. A heat exchange section 5 is provided in this space section 41 .

A heat exchanger may be attached to the heat exchange section 5 as shown in FIG. 3, or depending on the amount of heat exchanged, the heat radiation effect of the container 4 alone may be sufficient. As the refrigerant 3, a refrigerant with high electrical insulation properties, such as fluorocarbon, is used. The refrigerant 3 exists in the container 4 in two phases: a refrigerant liquid 31 and a refrigerant ring air 32.

The amount of heat lost by the semiconductor element 21 is transferred to the refrigerant liquid 31, and the refrigerant liquid 31 boils and becomes a refrigerant ring 31, which collects in the space 41 of the container 4. This refrigerant ring air 32 is cooled by the heat exchange section 5, becomes refrigerant liquid 31 again, and returns to the bottom of the container 4. The semiconductor element is cooled in the second manner.

When a high-frequency current is applied to the piezoelectric vibrator 11, the piezoelectric vibrator 11 generates high-frequency vibration, which is applied to the coolant 31, propagates through the coolant, and reaches the semiconductor element. This high-frequency vibration causes disturbances in the state of the coolant on the heat transfer surface of the semiconductor element, and the heat transfer is affected.

FIG. 4 shows a different embodiment, in which a base on which a piezoelectric vibrator 11 is installed forms a part of a closed container 4. In FIG. This reduces the size of the cooling device. The operating principle of cooling is the third
It is similar to the figure.

FIG. 5 shows a further different embodiment, in which a resonator 13 is added to the piezoelectric vibrator 11. This resonator 13 resonates with the vibration frequency of the piezoelectric vibrator and has directivity, concentrates the vibration energy on the semiconductor element 21 of the object to be cooled, and transfers heat from the semiconductor element 21 to the refrigerant liquid 31. further improves. 5 shows the case where a resonator 13 is added to the embodiment of FIG. 3, but other embodiments of FIGS.
It is also applicable to the illustrated embodiment.

〔Effect of the invention〕

In the cooling device for electronic equipment using the refrigerant immersion cooling method of the present invention,
By placing a piezoelectric vibrator facing the electronic device to be cooled and applying high-frequency vibrations to the refrigerant, the heat transfer was improved as described above, so the heat transfer could be improved with a very small amount of energy used to excite the piezoelectric vibrator. The results show that the heat transfer coefficient is 50 to 10
I was able to improve it by 0%. Additionally, it has become possible to downsize the device accordingly.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a cooling device for an electronic device according to an embodiment of the present invention, and FIGS. FIG. 11: Piezoelectric vibrator, 12: Base, 13: Resonator, 2: Semiconductor device (electronic device to be cooled), 21: Semiconductor element,
22: Substrate, 3: Refrigerant, 4: Container, 41: Space ≦y 1st Fertilizer ° Fig. 2]

Claims (1)

[Claims] 1) An electronic device to be cooled and one or more piezoelectric vibrators installed on a base and facing the electronic device are immersed in an electrically insulating refrigerant. These are housed in a container, the refrigerant is circulated by external power, and the electronic device to be cooled is cooled while applying high frequency vibration to the refrigerant by the piezoelectric vibrator. Equipment cooling system. 2) In the cooling device for electronic equipment according to claim 1), 1
A cooling device for electronic equipment, characterized in that a base on which one or more piezoelectric vibrators are installed forms a part of a container. 3) An electronic device to be cooled and one or more piezoelectric vibrators installed on a base and placed facing the electronic device are immersed in an electrically insulating refrigerant, and these are sealed. The refrigerant is housed in a container with a space left above the liquid level of the refrigerant, and a heat exchanger is provided in this space, and the piezoelectric vibrator applies high frequency vibration to the refrigerant while cooling the electronic equipment to be cooled. A cooling device for electronic equipment characterized by: 4) In the cooling device for electronic equipment according to claim 3), 1
A cooling device for electronic equipment, characterized in that a base on which one or more piezoelectric vibrators are installed forms part of a sealed container. 5) In the cooling device for electronic equipment according to claim 1), 2), 3) or 4), one or more piezoelectric vibrators installed on the base resonate at the vibration frequency and have directivity. A cooling device for electronic equipment characterized by adding a resonator.